Professor Golder Is Studying Hyperactivity in Preschool-Age Children

Multiple Choice

Professor Golder is studying hyperactivity in preschool-age children.She is concerned that differences in child rearing,diet,and home environment may affect her results.To minimize these potential pre-existing variables,she should be sure to do which of the following?

A) Use random assignment when forming her groups.
B) Include more than one independent variable.
C) Only measure a single dependent variable.
D) Only select children from homes with a high socioeconomic status (SES) .